Various industrial processes result in the production of waste streams containing toxic, hazardous, or radioactive waste species. Commonly these waste streams are in the form of aqueous solutions or dispersions that contain heavy metals and/or radionuclides in either dissolved or precipitated forms. These waste streams can also contain various other harmful compounds such as nitrates and phosphates. Examples of such waste streams are those wastes that result from plating operations for the aluminum plating of radioactive materials. Such plating operations result in a waste sludge material that contains nitrate compounds, nickel compounds, and radioactive compounds. These waste streams must be treated to meet various governmental regulations prior to disposal.
One way of treating these waste streams is to admix the waste with cement to form a grout admixture. This admixture is then allowed to cure and the waste compounds are immobilized in the hardened mass to an extent. A way to test the efficiency of the immobilization is to perform a toxicity characteristic leaching procedure (TCLP) test. This form of waste treatment is useful; however, the toxic, hazardous, or radioactive species frequently is not immobilized sufficiently and the cured waste/cement mass falls to pass the TCLP testing.
Other techniques used to treat such waste streams includes vitrification processes. In such processes the waste is added to a molten matrix, typically a glass matrix, where the aqueous and volatile matter is evaporated and the heavy metals, radioactive species, and other harmful compounds are entrapped in the glass material. The glass is then cooled and allowed to harden to solidify and immobilize the waste. However, such techniques are generally reserved for relatively higher level wastes due to the prohibitive costs of vitrification processing.
Thus, there exists a need in the art to develop processes for the efficient, economical, and reliable waste stream solidification and immobilization of harmful species. Ideally such an improved process would utilize the cement solidification technology, which is relatively inexpensive and commercially available, and improve upon that technology to provide for superior immobilization results.